Article based on a metal alloy of nickel, chromium and metalloid elements including microcrystalline precipitates, metal alloy and preparation method

Abstract

A description follows of an article based on a nickel-chromium-silicon metal alloy, including microcrystalline borides, obtained by the rapid solidification and subsequent thermal treatment of a nickel-chromium-boron-silicon metal alloy comprising from 39.0 to 69.4 atom % of nickel, from 11.8 to 33.9 atom % of chromium, from 7.6 to 27.4 atom % of boron and from 7.6 to 17.5 atom % of silicon. The above article is preferably a tape or a sheet or a fiber having high mechanical properties and is particularly resistant to oxidation.

What is claimed is:  
     
       1. An article based on a nickel-chromium-silicon metal alloy, including microcrystalline borides, obtained by rapid solidification, followed by thermal treatment at a temperature ranging from 700° C. to 950° C. for a time varying from 5 minutes for the upper temperature limit, to 100 hours for the lower temperature limit, of a nickel-chromium-boron-silicon metal alloy comprising from 39.0 to 69.4 atom % of nickel, from 11.8 to 33.9 atom % of chromium, from 7.6 to 27.4 atom % of boron and from 7.6 to 17.5 atom % of silicon. 
     
     
       2. The article according to  claim 1 , wherein the structure is a tape-form or filiform structure with a thickness lower than 50μm. 
     
     
       3. The article according to  claim 2 , wherein said thickness ranges from 5 to 40μm. 
     
     
       4. The article according to  claim 1 , wherein said thermal treatment is carried out at a temperature ranging from 750° C. to 880° C. for a time varying from about 30 minutes for the upper temperature limit to about 15 hours for the lower temperature limit. 
     
     
       5. The article according to  claim 1 , wherein said thermal treatment is carried out in an inert gas or under vacuum. 
     
     
       6. The article according to  claim 5 , wherein said thermal treatment is carried out at atmospheric pressure in an inert gas or under vacuum at a pressure lower than 10 −4  mbars. 
     
     
       7. A method for the preparation of an article based on a nickel-chromium-silicon alloy, including microcrystalline borides, which comprises: 
       (1) preparing a nickel-chromium-boron-silicon metal alloy comprising from 39.0 to 69.4 atom % of nickel, from 11.8 to 33.9 atom % of chromium, from 7.6 to 27.4 atom % of boron and from 7.6 to 17.5 atom % of silicon by melting of the constituent elements, or their partial alloys, and subsequent cooling, in an inert atmosphere or under vacuum;  
       (2) transforming said alloy obtained into end-articles in the desired form of tape, film, sheet or fiber by rapid solidification;  
       (3) subjecting said article to a thermal treatment in an atmosphere of an inert gas or under vacuum at a temperature ranging from 700° C. to 950° C., for a time varying from 5 minutes for the upper temperature limit to 100 hours for the lower temperature limit.  
     
     
       8. The method according to  claim 7 , wherein said rapid solidification is carried out by melt spinning or planar flow casting. 
     
     
       9. A method of making a superconductor element comprising depositing superconductor oxides onto the article of  claim 1  in the form of a tape or sheet. 
     
     
       10. A method of reinforcing comprising adding the article of  claim 1  in the form of a tape, sheet or fiber to a composite having an organic, metallic or pyroceram matrix. 
     
     
       11. The method according to  claim 10 , wherein the temperature is lower than or equal to 900° C. 
     
     
       12. A metal alloy comprising a quaternary alloy of the following general formula: 
       
         
           Ni x Cr y B w Si z    
         
       
       wherein 
       x+y+w+z=100; x+y=65-84.8;  
       x/y=1.5-4.5; w/z>1; 7.6<w<27.4, wherein said alloy comprises from 39.0 to 69.4 atom % of nickel, from 11.8 to 33.9 atom % of chromium, from 7.6 to 27.4 atom % of boron and from 7.6 to 17.5 atom % of silicon.